Tuberculosis (TB): Causes, Prevention, and the Global Picture

By /

A quick overview

Tuberculosis is an infectious disease caused by the bacterium Mycobacterium tuberculosis. It primarily affects the lungs, known as pulmonary TB, but it can impact nearly any organ. TB spreads through the air when someone with infectious pulmonary TB coughs, sneezes, sings, or even speaks in close, poorly ventilated places.

Even though it can be prevented and treated, TB continues to be one of the biggest infectious threats to humanity. In 2023, an estimated 10.8 million people became ill with TB, and around 1.25 million died, making it the leading infectious killer worldwide. World Health Organisation CIDRAP

How TB infection happens

  • Exposure to Infection (LTBI): Inhaling airborne droplet nuclei can lead to latent TB infection (LTBI). People with LTBI have no symptoms and are not contagious. However, they carry a lifetime risk of developing active disease, which is higher if their immunity is weakened.
  • Active TB disease: When the immune system can’t control the bacteria, active TB develops. This usually presents as a persistent cough lasting two weeks or more, along with fever, night sweats, chest pain, fatigue, and weight loss. Extrapulmonary TB varies depending on the affected organ, such as lymph nodes, pleura, or spine.

Who is most at risk of developing the disease? TB risk is greatly influenced by social and medical factors. Five main drivers stand out worldwide: undernutrition, HIV infection, alcohol-use disorders, smoking, and diabetes. Poverty and overcrowding also play a significant role. World Health Organization+1

The causes and drivers—beyond the bacterium

Calling M. tuberculosis the “cause” of TB is only part of the truth. The bacteria thrive where:

  • Poverty and crowding increase exposure to factors like dormitories, mines, prisons, and shelters.
  • Malnutrition weakens immunity and is now seen as the biggest contributor to TB risk in many high-burden countries, according to the World Health Organization.
  • Co-morbidities like HIV and diabetes raise the risk of developing the disease from infection.
  • Tobacco and alcohol use weaken the body’s defenses and are associated with worse outcomes. World Health Organization

Diagnosis—what “early detection” looks like today

Modern TB programs aim to find and treat TB early, before it spreads:

  • Rapid molecular tests are the starting point. The WHO recommends molecular tests, such as Xpert and Truenat, as the first step for diagnosing suspected TB and detecting drug resistance. These tests are quick and much more accurate than smear microscopy. TB Knowledge Sharing
  • Chest X-rays help find possible cases, while culture confirms challenging cases. Testing for drug susceptibility helps determine the appropriate treatment.
  • Contact investigation, which involves testing people who live with or are in close contact with a TB patient, is an essential strategy for detecting both active disease and latent infection early.

Treatment—shorter, safer, and all-oral options

Drug-susceptible TB (DS-TB)

  • The long-standing standard is 6 months of combination therapy.
  • The WHO has also supported a shorter 4-month option, a rifapentine and moxifloxacin-based regimen, for eligible people with DS-TB. This option can improve completion and convenience. World Health Organization

Drug-resistant TB (DR-TB)

  • The breakthrough is the 6-month all-oral BPaLM treatment (bedaquiline, pretomanid, linezolid, moxifloxacin) recommended by WHO for various types of MDR/RR-TB. Results are better, and treatment is much easier than the previous 18 to 20 month plans.

Even with progress, access remains uneven. In 2023, only about 2 in 5 people with drug-resistant TB around the world received treatment. Closing this gap is urgent. World Health Organization

Preventing TB: from household to national policy

1) TB Preventive Treatment (TPT)

People at higher risk, such as household contacts of pulmonary TB, individuals living with HIV, and certain clinical risk groups, can get antibiotics to prevent TB disease. WHO-recommended options include:

  • 3HP: once-weekly isoniazid and rifapentine for 3 months
  • 1HP: daily isoniazid and rifapentine for 1 month
  • 3HR: daily isoniazid and rifampicin for 3 months.
  • Six to nine months of isoniazid alone is still used where newer regimens aren’t available. NCBI

2) Infection prevention & control (IPC)

  • Ventilation and sunlight in homes, clinics, and workplaces.
  • Respiratory protection, such as N95 or FFP2 masks, in high-risk health settings.
  • Cough etiquette and quick diagnosis and treatment to reduce transmission at the source.

3) Vaccination

  • BCG protects young children from severe TB, including meningitis and miliary TB. However, its effectiveness against adult pulmonary TB varies. New vaccines are undergoing late-stage trials. Notably, M72/AS01E began large Phase 3 studies in 2024, which raises hopes for improved protection for adults. The Gates Medical Research Institute

The global burden—where we stand now

  • Illness and deaths: In 2023, 10.8 million people got sick and 1.25 million died from TB. Deaths are decreasing slightly, but the number of cases stays high. World Health Organization CIDRAP
  • Diagnosed cases: 8.2 million people were newly diagnosed in 2023. This is the highest number since global monitoring started. It shows both the continued spread of the disease and improved identification of cases. Pan American Health Organization
  • Drug resistance: About 421,000 people developed rifampicin-resistant or multidrug-resistant TB in 2023. World Health Organization
  • Economic toll: Around half of TB-affected households worldwide experience catastrophic costs, which exceed 20% of their annual income, even though TB drugs are “free.” This is due to expenses for transport, nutrition, and lost wages. World Health Organization

Goals and momentum

  • The WHO End TB Strategy aims for significant reductions by 2030, targeting an 80% drop in incidence and a 90% reduction in deaths. By 2035, the goals become even more ambitious, with a 90% decrease in incidence and a 95% reduction in deaths compared to 2015. World Health OrganizationStop TB Partnership
  • In 2023, UN Member States set targets to be met by 2027, such as increasing treatment and preventive therapy to reach tens of millions. To achieve these goals, we will need consistent funding, quick adoption of shorter treatment regimens, and focus on social factors like nutrition and poverty. Stop TB Partnership

What action looks like (practical, layered, global)

For individuals & families

  • Seek evaluation for any cough lasting two weeks or more, fever, weight loss, or night sweats, especially after close contact with someone who has TB.
  • If you live with someone who has TB, or if you have HIV or diabetes, ask about TPT and screening.
  • Improve airflow at home and work. Follow proper cough etiquette. Complete all prescribed treatment.

For healthcare teams

  • Use WHO-recommended rapid molecular tests as the first test.
  • Offer TPT to eligible contacts and high-risk groups.
  • Prefer shorter, all-oral regimens where guidelines allow. Monitor for side effects and support adherence through digital tools, peer support, and enablers.

For policymakers & partners

  • Invest in nutrition support, social protection, and primary care to address the main risk factors.
  • Make sure drug-resistant TB programs use 6-month all-oral regimens. Also, expand lab capacity for resistance testing.
  • Provide funding for community-based case-finding, contact tracing, and TB data systems.
  • Support TB vaccine research and development. Plan ahead for the quick rollout of effective new vaccines.

Key takeaways

  • TB is airborne, preventable, and curable. It still caused 10.8 million illnesses and about 1.25 million deaths in 2023.World Health OrganizationCIDRAP
  • The main risk factors are undernutrition, HIV, alcohol use, smoking, and diabetes. Therefore, TB control must extend beyond just medication. World Health Organization
  • Diagnostics and treatments are quicker and more concise than before. The duration for drug-susceptible tuberculosis (DS-TB) is now 4 months, while the all-oral treatment for drug-resistant tuberculosis (DR-TB) takes 6 months. World Health Organization
  • Preventive treatment and BCG for infants save lives now. New vaccines are also on the way. NCBI The Gates Medical Research Institute
  • To end TB, the world must combine scientific tools with nutrition, poverty reduction, and social support. This will help close the cost gap that families face. World Health Organization

Frequently Asked Questions (FAQs) on Tuberculosis (TB)

1. What causes tuberculosis (TB)?

TB is caused by a bacterium named Mycobacterium tuberculosis. It mainly spreads through the air. When someone with active pulmonary TB coughs, sneezes, or speaks near others, they can transmit the disease.

2. Is TB contagious to everyone who is exposed?

Not always. Most people who inhale TB bacteria do not get sick right away. They may develop latent TB infection (LTBI), which means the bacteria are inactive in their body. Only about 5 to 10% of infected people will develop active TB disease during their lifetime. However, the risk is much higher if their immune system is weak, such as in cases of HIV, diabetes, or malnutrition.

3. What are the symptoms of active TB?

The most common symptoms include:

  • Persistent cough, lasting more than 2 weeks, sometimes with blood.
  • Fever and night sweats.
  • Unexplained weight loss.
  • Fatigue and chest pain.
  • Other forms of TB, outside the lungs, may affect the spine, brain, lymph nodes, or kidneys. This can cause different symptoms.

4. Who is most at risk of developing TB?

Anyone can get TB, but the risk is higher for:

  • People with HIV/AIDS
  • Those who are undernourished
  • People with diabetes
  • Smokers and those with alcohol use disorders
  • People living in overcrowded or poorly ventilated places, such as slums, prisons, mines, and shelters

5. How is TB diagnosed?

TB can be diagnosed through:

  • Rapid molecular tests, which are the World Health Organization’s recommended first choice, include Xpert and Truenat.
  • Chest X-ray.
  • Sputum smear microscopy and culture.
  • Drug resistance testing to identify the right treatment.

6. How is TB treated?

  • Drug-susceptible TB: usually treated with a combination of antibiotics for 4 to 6 months.
  • Drug-resistant TB: requires stronger medicines, but now shorter 6-month all-oral regimens are available in many places. Treatment must be completed fully, even if symptoms improve, to prevent relapse and resistance.

7. What is drug-resistant TB (DR-TB)?

Drug-resistant TB happens when TB bacteria no longer respond to the most effective medicines.

  • MDR-TB: resistant to isoniazid and rifampicin.
  • RR-TB: resistant to rifampicin only.
  • XDR-TB: resistant to even more drugs.
    It is harder to treat but can still be cured with the latest all-oral regimens.

8. Can TB be prevented?

Yes. Prevention includes:

  • BCG vaccination for infants protects against severe childhood TB.
  • TB preventive treatment (TPT) is for people at risk, such as household contacts and HIV-positive individuals.
  • Improving ventilation, nutrition, and reducing crowding can help.
  • Early detection and treatment of active cases stop the spread.

9. What is latent TB infection (LTBI), and why does it matter?

LTBI means that the bacteria live in the body without causing symptoms. People with LTBI are not contagious, but they can develop active TB later, especially if their immune system becomes weak. Preventive treatment can stop this progression.

10. How big is the TB problem globally?

  • Around 10.8 million people got sick with TB in 2023.
  • About 1.25 million people died from it, making TB the world’s second biggest infectious killer after COVID-19.
  • TB is most common in South-East Asia, Africa, and the Western Pacific.

11. Is TB still curable today?

Yes. With timely diagnosis and the right medicines, most TB cases can be cured. The main challenges are late detection, incomplete treatment, poverty, and drug resistance.

12. Why is TB still a global health challenge?

Despite effective treatment, TB continues to spread because of:

  • Poverty and malnutrition
  • Weak healthcare systems in high-burden countries
  • Stigma and lack of awareness
  • Drug resistance and slow rollout of new tools.
  • Ending TB requires both medical progress and strong social support systems.

Reference

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top